Investigations into prevention have included prophylactic administration of thiamine and pyridoxine. High cool season productivity of good quality 3. Grazing of hay aftermath from toxic pastures should be avoided. The compound accumulates in the CNS to directly interact with serotonergenic receptors in the motor and sensory nerve nuclei of the brain and spinal cord. “Signs include breathing difficulties and blue-coloured gums and the animal will usually die,” she said. Australian Veterinary Journal 65:218-220, Bourke CA, Colegate SM, Rendell D (2003) Efficacy of the prophylactic use of thiamine and pyridoxine in sheep during an outbreak of Phalaris aquatica âPolioencephalomalacia-like sudden deathâ poisoning. Gross pathology may reveal a green-grey discolouration of the lateral geniculate body in the brain and brainstem, with this discolouration also sometimes seen in the renal medulla. Phalaris canariensis is commonly used for bird seed. It has been proven that the level of noxious alkaloids responsible for the chronic staggers syndrome are increased during certain periods, this being influenced by interacting plant, animal and environmental factors. 8. 'Phalaris staggers' is an in- coordination syndrome that is associated with the ingestion of some varieties of phalaris (Phalaris aquatica) at a time when it contains toxic alkaloids. Again there is no treatment and stock should be removed immediately from the paddock with as little stress as possible to avoid eliciting further mortalities. All varieties can cause phalaris poisoning. Some lack the ability to rise and may appear hyperaesthetic and struggle when approached. Tolerates heavy grazing once established (particularly semi-winter dormant cultivars) 5. Intraruminal Co administration is not preventative for these cases. Phalaris toxicity, or Phalaris staggers can affect sheep that are grazing on fresh breaks of phalaris. Australian Veterinary Journal 81:698-700, Healy PJ, Harper PAW & Dennis JA (1990) Bovine citrullinaemia: a clinical, pathological, biochemical and genetic study. With a flush of new growth across many grazing regions following recent rainfall after a prolonged dry period, there is currently an increased risk of livestock suffering from phalaris toxicity as a result of consuming young phalaris grass. Habitat Top of page. The lesion seen is diffuse spongiform change involving astrocytes and sparing neurones, the latter being affected in thiamine-deficient PE. 6. Reed canarygrass (Phalaris arundinacea) is a stout, erect, perennial grass that is a major weed in winter crops and pastures worldwide. “If phalaris toxicity is suspected stock should be removed immediately, but slowly, from pasture.” To avoid phalaris toxicity it is best to avoid grazing phalaris during the first six weeks of new growth or to limit the intake of phalaris during the first two days of grazing to just a few hours per day. The toxin responsible is unknown, although it is considered that ruminants are able to detoxify this toxin provided it is not ingested too rapidly or in excess (Bourke et al 1988). Australian Veterinary Journal 67: 255-258, Finnie JW, Windsor PA, Kessell AE, 2011. Occasionally, phalaris sudden death syndrome can occur. “Cobalt supplementation may help prevent phalaris staggers, but not the sudden death syndrome.”. P. arundinacea is a highly variable species, varying in height, size and shape of inflorescence, and coloration. Tolerates waterlogging and moderate salinity. Consideration of these risk factors suggests that producers should aim to avoid putting hungry stock on freshly-shooting phalaris dominant pastures, especially following periods of frosts or moisture stress. The poisonous potential of Phalaris aquatica is dynamic and is a function of interacting plant, animal, environmental and management factors. Phalaris staggers is sometimes a problem, particularly when rapid regrowth occurs after a cold or dry spell, but can be avoided by not grazing affected stands at that time or by dosing stock with cobalt. Deep root system helps dry soil profile and reduces rate of soil acidification. Reed canarygrass (Phalaris arundinacea L.), a related plant and a widespread native grass found growing throughout most of the United States, is managed as forage for livestock and alleged to have alkaloid toxicity concerns. Requires good grazing management to maintain grass–legume balance and feed quality. The prevalence is usually about 1%, being much lower than seen with cases of PE-like sudden death (Bourke & Carrigan 1992). Fertile soils such as those nitrogen-enriched with leguminous plants, or fertilised with superphosphate have also been found to have higher levels of the tryptamine alkaloids. Fresh regrowth can at times be dangerous to live stock due to the presence of toxic alkaloids. Some Phalaris species contain gramine, which can cause brain damage, other organ damage, central nervous system damage and death in sheep although Phalaris aquatica is said to be non-toxic. Flat, green leaf blades occur from spring to early summer, but tend to turn brown as the summer progresses. 4. 7. From autumn through to late winter it may be wise to test the toxic potential of a paddock by placing a group of sentinel sheep onto the paddock 48 hours before the entire flock is given free access. Phalaris staggers is an incoordination syndrome that is associated with the ingestion of phalaris (Phalaris aquatica) which contains dimethyltryptamine alkaloids (Finnie et al 2011). “Farmers should also manage stocking rates and feed hay before giving animals access to pasture to ensure they are not overly hungry and consume less,” Dr Gibney said. It has also been known to accumulate high levels of selenium, causing selenium toxicity in horses. If the stock have been transported or yarded for a period of time without access to food, they should be fed before being placed on the pasture. This was based on a number of reasons outlined in the paper such as the rate of action of the toxic antagonistic agent was too rapid for the dose administered of the prophylactic agent (Bourke et al 2003). PHALARIS can harbour toxic alkaloids which cause a serious nervous syndrome and Phalaris staggers. It is important to remember however that they serve no purpose in the prevention of the other forms of toxicosis. Deep root system helps dry soil profile and reduces rate of soil acidification 2. Suggestions include agents known to produce thiamine-deficient PE in sheep such as thiamine antagonists (thiaminases) or amine co-substrates. Continuously grazing or set-stocking pastures to keep new growth at a minimum especially during the autumn and winter months may assist. Both sheep and cattle may suffer staggers or sudden death after grazing phalaris, although cattle are less susceptible than sheep. The study in question failed to demonstrate any protective effect of these substances, however did not completely dismiss the possibility of their use for prophylaxis. A perennial grass found mainly in lowland pasture on fertile soils. In contrast, phalaris sudden death sydrome is caused by high levels of ammonia in the animal’s system. As the toxins responsible for the other conditions remain unknown, there has been speculation on associations between increased incidence of outbreaks and these interacting factors. Phalaris toxicity can cause both a sudden death syndrome and a staggers syndrome. Dr Gibney said sudden death syndrome usually develops 12 to 36 hours after the animal has been on pasture. “If phalaris toxicity is suspected stock should be removed immediately, but slowly, from pasture.” To avoid phalaris toxicity it is best to avoid grazing phalaris during the first six weeks of new growth or to limit the intake of phalaris during the first two days of grazing to just a few hours per day. “If phalaris toxicity is suspected stock should be removed immediately, but slowly, from pasture.”. The poisonous potential of phalaris pastures is dynamic. Increased alkaloid content in the foliage of P.aquatica has been measured during periods of moisture stress, frost conditions and decreased light intensity, such as overcast weather or shading. “Sheep that start staggering may improve, but may be left with staggers for life,” she said. 1. This neurological syndrome results from the repeated or protracted ingestion of methylated tryptamine alkaloids present in P.aquatica. It causes vomiting, anorexia, too much salivation, depression and dilated pupils in cats. The animals suffer from respiratory distress, their mucous membranes becoming cyanotic. Toxic components All parts of P. arundinacea contains tryptamine alkaloids. Australian Veterinary Journal 81:637-638, Bourke CA, Colegate SM & Rendell D (2003) Clinical observations and differentiation of the peracute Phalaris aquatica poisoning syndrome in sheep known as âPolioencephalomalacia-like sudden deathâ. The risk of stock developing phalaris staggers is a function of soil cobalt levels, levels of soil ingestion and levels of phalaris dominance and palatability. Nitrate compounds have also been postulated as the causative agent as it has been documented that phalaris pastures can attain nitrate nitrogen concentrations >2920Î¼g/g, with the potentially toxic concentration for sheep only 1000Î¼g/g (Bourke & Carrigan 1988). Regrowth after grazing or mowing also shows a considerable increase in alkaloids. Wallerian degeneration may also be seen associated with the white matter (axons) of the brain and spinal cord. Animals that are newly introduced to phalaris and those with alterations in feed intake, as occurs in cell grazing systems, are considered at greater risk of intoxication. This causes a functional rather than structural nervous derangement, which is demonstrated by the clinical signs being precipitated with disturbance of the flock. Clinical signs can develop as soon as 1-3 weeks following the introduction to the pasture especially with the older, high tryptamine cultivars. Excellent drought survival ability 2. Once moved, there should be no more new cases. Few pests and diseases 8. Phalaris aquatica L. Common name: Toowoomba canary grass: Status: Not declared noxious in Victoria. However, with the new, low tryptamine varieties such as Sirolan, much longer periods of grazing (3-4 months) may be needed to induce staggers (Bourke et al 2003) plus a delay in development of clinical signs can occur even after being removed from the incriminating pasture, with cases developing up to 3-4 months later. Responsive to increased soil fertility. Tolerates waterlogging and moderate salinity 7. Soil requirements: It is best suited to high-fertility, deep, heavy-textured soils, but soil type, soil depth and grazing management become more critical as rainfall decreases. Alternatively, top dressing the pasture with Co or individually drenching each sheep so a minimum of 28mg per head per week is given will allow potentially toxic pasture to be grazed with no adverse consequences (Blood et al 2000). The cardiac from of sudden death form on phalaris pastures involves a sudden onset of a cardiorespiratory disorder without neurological signs. Few pests and diseases. Toxic levels of cyanide (20mg or greater/100g of hydrocyanic acid) have been measured in phalaris plants from toxic pastures (Bourke & Carrigan 1992), thus a cyanogenic poison has been investigated. Seasonal and weather patterns appear to affect alkaloid concentration, as most toxicity occurs in autumn and in times of drought. To avoid phalaris toxicity it is best to avoid grazing phalaris during the first six weeks of new growth or to limit the intake of phalaris during the first two days of grazing to just a few hours per day. They display incoordination and proprioceptive deficits with frequent falling over. Cardiorespiratory signs can be seen with the nervous forms of intoxication, probably due to the increased effort and strain on the cardiovascular system due to the nervous incoordination, rather than any direct effect of the toxin on myocardial function The affected animals remain conscious throughout, however if recumbent for a prolonged period, may become comatose and develop cerebral convulsions. Sometimes known as Reed Canary Grass. Excellent drought survival ability. Burning annual ryegrass pastures in the fall destroys most of the galls colonized by bacteria and minimizes the risk of toxicity in the following season. Tolerant of heavy soils that are wet in winter and survives severe summer droughts. Phalaris aquatica with its numerous cultivars is a much-valued perennial grass species widely used in improved pastures across south-eastern Australia. 'Staggers' is a term used to describe a brain disorder characterised by an unsteady stumbling gait, sheep may be unable to stand. It has also been noted that the incidence of this form of phalaris sudden death may be associated with seasonal increases of N-methyltryamine in P.aquatica (Bourke et al 2003). With the flush of new growth across the region following recent rainfall after a prolonged dry period, there is currently an increased risk of livestock suffering from phalaris toxicity as a result of consuming young phalaris grass. The incidence of cardiac sudden death syndrome does appear to be greatest during the first few months of new growth, typically autumn to early winter (Bourke & Carrigan 1992): thus it is wise avoid grazing phalaris dominant pastures during this period. If no clinical cases have been seen within this time, the pasture is generally considered safe, and it is assumed that the animals can adequately adapt to the toxic challenge. These lesions can usually only be detected in cases greater than several weeks duration (Bourke et al 1988). II: toxic disorders and nutritional deficiencies. It is advised that two bullets are given to prevent a calcium carbonate coating building up around the bullet, which would decrease effective absorption of Co. Intraruminal grinders are also available for this purpose. But some farmers have moved away from the species because it causes phalaris toxicity, or staggers, a condition that can cause abrupt heart failure or a … There is no effective treatment, but animals should be immediately moved to phalaris-free pastures. In its early stages of growth (usually the first six weeks) phalaris grass contains toxic alkaloids, which if grazed, can lead to animals developing phalaris staggers. Animals are paretic, ataxic, have a generalised muscle tremor including head nodding and jaw champing. To produce the signs seen, the toxin must act either on the cardiorespiratory centres in the medulla oblongata or on the vagal nerve endings as they innervate the heart. It prefers fertile, seasonally moist sites (Muyt 2001). Some Phalaris species contain gramine, which, in sheep and to a lesser extent in cattle, is toxic and can cause brain damage, other organ damage, central nervous system damage, and death. Death or recovery can occur over the ensuing weeks or months, depending on the chronicity of ingestion and the severity of clinical signs.